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Pink Primrose Orchid
Caladenia rosea K.W.Dixon & Christenh. 2018

Synonyms

Notes

Restricted to a small area of south-western WA, the Pink Primrose Orchid looks almost exactly like the common and widespread Cowslip Orchid (Caladenia flava) except for being pink rather than yellow in colour (hence the scientific name rosea). In fact, it closely resembles some of the occasionally encountered hybrids between the Cowslip Orchid and either the Pink Fairy Orchid (Caladenia latifolia) or the Little Pink Fairy Orchid (Caladenia reptans), but forms almost pure populations in areas where the regular yellow form of the Cowslip Orchid is less abundant.

The Pink Primrose Orchid is restricted to a small area of the Darling Scarp south of Perth where it grows in lateritic soil in open Jarrah–Marri woodland and is typically common. Curiously, it forms almost pure populations which largely replace the normal yellow form of the Cowslip Orchid. As the Pink Primrose Orchid does not produce nectar, both its colour and scent are believed to mimic the co-occurring Swan River Myrtle (Hypocalymma robustum) as a way of attracting pollinators. This appears to provide an ecological advantage over the standard yellow flower colour of the Cowslip Orchid.

While the Pink Primrose Orchid has been described as a separate species, its exact status is uncertain, and it could simply be a pink colour form of Caladenia flava which has evolved to fill a specific ecological niche. Some flowers still show some yellow colouration which also points to the Cowslip Orchid as its ancestor. Alternatively, it could have originated from hybrids between Caladenia flava and Caladenia latifolia or reptans as an example of hybrid speciation. Interestingly, it grows in the company of another Cowslip Orchid look-alike, the White Primrose Orchid (Caladenia lateritica), which has white instead yellow or pink flowers and could likewise simply be an unusual colour form of the Cowslip Orchid.

Photos

Caladenia rosea
The flowers are similar to those of the Cowslip Orchid (Caladenia flava), but are mostly pink instead of yellow. (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
The flowers look very similar to those of the Spectacular Spider Orchid (Caladenia × spectabilis). (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
The flowers are generally highly variable in colour. (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
A particularly spectacular colour form. (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
A pink and white colour form. (Teesdale, WA, 15 / 09 / 2024)
Caladenia rosea
Some plants have extensive white colouration and can be difficult to separate from the White Primrose Orchid (Caladenia lateritica). (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
Others have preserved traces of the original yellow colour of the Cowslip Orchid (Caladenia flava). (Teesdale, WA, 15 / 09 / 2024)
Caladenia rosea
Close-up view of the labellum. (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
The orchids often form small clonal colonies. (Teesdale, WA, 17 / 09 / 2023)
Caladenia rosea
The Pink Primrose Orchid is thought to mimic the Swan River Myrtle (Hypocalymma robustum) in both colour and scent. (Teesdale, WA, 15 / 09 / 2024)
Caladenia rosea
The Pink Primrose Orchid grows in lateritic soil in open Jarrah–Marri woodland in a restricted area of the Darling Scarp. (Teesdale, WA, 17 / 09 / 2023)

References